Ferromagnetic spin correlations in a few-fermion system

TL;DR

This paper investigates how repulsive interactions in a small fermion system lead to ferromagnetic correlations, using exact calculations and experimental probes, approaching the Stoner limit with few atoms.

Contribution

It provides the first detailed analysis of spin correlations in a few-fermion quasi-1D system, highlighting the effects of interactions and energy discretization.

Findings

Repulsive interactions induce ferromagnetic correlations.

Ejection probability serves as an experimental probe.

System approaches the Stoner limit with more than five atoms.

Abstract

We study the spin correlations of a few fermions in a quasi one-dimensional trap. Exact diagonalization calculations demonstrate that repulsive interactions between the two species drives ferromagnetic correlations. The ejection probability of an atom provides an experimental probe of the spin correlations. With more than five atoms trapped, the system approaches the itinerant Stoner limit. Losses to Feshbach molecules are suppressed by the discretization of energy levels when fewer than seven atoms are trapped.